The present invention relates generally to treatment of the subluxation or dislocation of the distal end of the clavicle resulting from stretching or rupture of the acromioclavicular or coracoclavicular ligaments, and specifically to a support or brace for reducing an acromioclavicular dislocation by the immobilization and elevation of the acromion and depression of the distal clavicle.
The acromion, the outer end of the spine of the scapula, articulates with the clavicle to form the outer angle of the human shoulder. The main stability of this joint is provided by the superior acromioclavicular and coracoclavicular ligaments. Injury to the acromioclavicular joint may result in the stretching of these ligaments and of the synovial capsule, or the rupture of the capsule and the acromioclavicular ligament. Severe ligamentous injury involves the rupture of both the acromioclavicular and coracoclavicular ligaments. These injuries result in the elevation of the distal end of the clavicle.
While surgery may be indicated in severe disruptions of the acromioclavicular and coracoclavicular ligaments, rupture of the acromioclavicular ligaments or stretching of the synovial capsule or the acromioclavicular ligament are commonly treated by closed methods which allow the natural reparative process to take place. Of primary import in advancing this natural fibrous repair are (a) the elevation of the acromion, (b) the depression of the elevated clavicle toward the elevated acromion, and (c) constant immobilization of the joint to prevent further strain or disruption of the reparative process.
Commonly employed methods of closed treatment have included a claviculo-ulnar reduction harness for relocating the acromioclavicular joint and a forearm sling hung from the neck to provide immobilization and ninety degree flexion of the elbow. The Kenny-Howard sling, as known in the art, employs a forearm sling and reduction straps attaching the sling to a shoulder pad. These reduction straps, when tensioned, depress the distal end of the clavicle and exert an upward force on the acromion via the humerus to maintain reduction. In addition, a positioning strap exerts a medial force to maintain the position of the reduction straps and shoulder pad when the unrestrained arm moves away from the torso.
Other slings have included neck straps to hold the affected arm in ninety degree flexion. Also, straps have been devised which attach to the wrist and provide a tensioning force on the neck strap by encircling the buttock on the affected side.
However, the Kenny-Howard sling and other such devices are not without their disadvantages. The reduction force on the distal clavicle is limited to the tension produced on the claviculo-ulnar straps by the weight of the forearm applied directly to the shoulder pad through said straps.
Also, neck straps produce uncomfortable pressures on the patient's neck and potentially disruptive forces on the trapezius muscles which play a major role in the articulation of the acromioclavicular joint. Straps which encircle the buttock are uncomfortable and provide only marginal immobilizing forces in ambulatory patients.
In addition, while prior art devices often include a strap circumflexing the thorax which provides a medial force on the sling, the arm is still relatively free to move. Thus when the patient leans forward or walks, the slung arm moves forward relative to the torso presenting a risk of the destruction of the newly formed fibrous repair.